An "ardent critic" refers to someone who strongly and passionately disagrees or disapproves of something or someone, and is vocal about expressing their negative opinions. Full definition
At the other side of the spectrum, John Locke came to be known as the most ardent critic of these concepts, believing that there was no evidence for innate ideas whatsoever. (blog.politics.ox.ac.uk)
Summary: A fine example of a remaster done right, DmC is a fast paced action game that offers a wealth of customisation options to appease even the most ardent critic of the game. (impulsegamer.com)
Not even the spread of the economic scourge to at least 30 other states could absolve him of blame by ardent critics. (nigeriapoliticsonline.com)